Add XTEA encryption support in libavutil

Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 165 insertions, 0 deletions

diff --git a/libavutil/xtea.c b/libavutil/xtea.c
new file mode 100644
index 0000000000..138657f88b
--- /dev/null
+++ b/libavutil/xtea.c
@@ -0,0 +1,165 @@
+/*
+ * A 32-bit implementation of the XTEA algorithm
+ * Copyright (c) 2012 Samuel Pitoiset
+ *
+ * loosely based on the implementation of David Wheeler and Roger Needham
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/intreadwrite.h"
+
+#include "avutil.h"
+#include "common.h"
+#include "xtea.h"
+
+void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
+{
+    int i;
+
+    for (i = 0; i < 4; i++)
+        ctx->key[i] = AV_RB32(key + (i << 2));
+}
+
+static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
+                           int decrypt)
+{
+    uint32_t v0, v1;
+    int i;
+
+    v0 = AV_RB32(src);
+    v1 = AV_RB32(src + 4);
+
+    if (decrypt) {
+        uint32_t delta = 0x9E3779B9, sum = delta * 32;
+
+        for (i = 0; i < 32; i++) {
+            v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
+            sum -= delta;
+            v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
+        }
+    } else {
+        uint32_t sum = 0, delta = 0x9E3779B9;
+
+        for (i = 0; i < 32; i++) {
+            v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
+            sum += delta;
+            v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
+        }
+    }
+
+    AV_WB32(dst, v0);
+    AV_WB32(dst + 4, v1);
+}
+
+void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
+                   uint8_t *iv, int decrypt)
+{
+    int i;
+
+    while (count > 0) {
+        if (decrypt) {
+            xtea_crypt_ecb(ctx, dst, src, decrypt);
+
+            if (iv) {
+                for (i = 0; i < 8; i++)
+                    dst[i] = dst[i] ^ iv[i];
+                memcpy(iv, src, 8);
+            }
+        } else {
+            if (iv) {
+                for (i = 0; i < 8; i++)
+                    dst[i] = src[i] ^ iv[i];
+                xtea_crypt_ecb(ctx, dst, dst, decrypt);
+                memcpy(iv, dst, 8);
+            } else {
+                xtea_crypt_ecb(ctx, dst, src, decrypt);
+            }
+        }
+
+        src   += 8;
+        dst   += 8;
+        count -= 8;
+    }
+}
+
+#ifdef TEST
+#include <stdio.h>
+#undef printf
+
+#define XTEA_NUM_TESTS 6
+
+static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
+    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
+    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
+    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
+    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
+};
+
+static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
+    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
+    { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
+    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
+    { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
+};
+
+static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
+    { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
+    { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
+    { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
+    { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
+    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
+};
+
+int main(void)
+{
+    AVXTEA ctx;
+    uint8_t buf[8];
+    int i;
+
+    for (i = 0; i < XTEA_NUM_TESTS; i++) {
+        av_xtea_init(&ctx, xtea_test_key[i]);
+
+        av_xtea_crypt(&ctx, buf, xtea_test_pt[i], 1, NULL, 0);
+        if (memcmp(buf, xtea_test_ct[i], 8)) {
+            printf("Test encryption failed.\n");
+            return 1;
+        }
+
+        av_xtea_crypt(&ctx, buf, xtea_test_ct[i], 1, NULL, 1);
+        if (memcmp(buf, xtea_test_pt[i], 8)) {
+            printf("Test decryption failed.\n");
+            return 1;
+        }
+    }
+    printf("Test encryption/decryption success.\n");
+
+    return 0;
+}
+
+#endif